


Grimlock and Guilt

by Delirious21



Category: Transformers: Robots in Disguise (2015)
Genre: M/M, Oral Sex, Plot What Plot/Porn Without Plot, Size Difference, Sticky Sexual Interfacing, Valve Fingering (Transformers)
Language: English
Status: Completed
Published: 2019-02-09
Updated: 2019-02-09
Packaged: 2019-10-24 18:53:14
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 2,666
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/17709656
Author URL: https://archiveofourown.org/users/Delirious21/pseuds/Delirious21
Summary: The day after the Minitron insanity, Grimlock woke up with a sinking feeling of guilt lining his tanks. He knew it wasn't all his fault that he'd attacked the team, but he still blamed himself for not being able to win control over his own body. Everyone was still healing from the wounds he'd delivered; especially Sideswipe. Being the loyal mech he is, Grimlock decides that he has to do something to make it up to the red mech. (Takes place after RiD 2015 episode 8)





	Grimlock and Guilt

**Author's Note:**

> Usually don't write RiD, but hey, it happened. Enjoy, smut lovers!

He couldn’t explain it. Well, not entirely. He could explain the obvious: Sideswipe was the one he’d beat up the most: the one Grimlock owed the most to. The day after the Minitron insanity, Grimlock woke up with a sinking feeling of guilt lining his tanks. He knew it wasn't all his fault that he'd attacked the team, but he still blamed himself for not being able to win control over his own body. Everyone was still healing from the wounds he'd delivered; especially Sideswipe. Grimlock stretched, shaking off some of the dew that had collected on his armor while he recharged outside. He heard voices near the Alchemor. Probably Bee; always the early riser.

He stood and began his search for Sideswipe. He couldn't ignore the guilt in his tanks, so he decided to attack it head on instead. Maybe he'd even get to punch something along the way, wouldn’t that be a relief!

At the main ship controls, Fixit tinkered with some exposed wires and Bumblebee helped Strongarm practice reciting the Autobot Code and regulations. Denny and Russel were nowhere to be seen. 

The air was oddly dry: all the better for Grimlock to pick up on the one scent he planned to follow. His nostrils flared at the distinct, somewhat polish laden trail. Bee spotted him and called him over. “Hey, Grimlock! Come over here, I want to talk to you for a second.”

Grimlock turned his giant Rex head. “Oh, okay. Sure thing.”

Bee folded his arms over his chassis and leaned back against the console a bit once Grimlock reached him. “How are you feeling, big guy?”

Grimlock scratched his neck. “I feel fine, I guess.”

Bee arched an optical ridge. “Yesterday was rough, but I want you to know that none of us blame you. Minitron took control over all of us, Grim. We know what it’s like to not be in control. Right Strongarm?”

Strongarm glanced up from the datapad she was furiously studying. “Yes sir. Listen, Grimlock, we understand. Don’t beat yourself up about it, okay?”

Grimlock nodded. “Right. Um. . . you guys know where Sideswipe’s at?”

“He went for a drive about a half hour ago. He had to blow off some steam,” Bumblebee answered.

Grimlock didn’t give up hope. Sideswipe had to come back eventually. And, that evening, he did: tires squealing, horn blaring: the whole shebang. The second he was through the gate, Grimlock ran over. 

“Woah, slow down there, Grim. What’s got your tail in a twist?” Sideswipe grinned as he transformed into his bipedal form.

Suddenly, Grimlock wasn’t sure what he was doing. In dino-mode, he tried to scratch his neck but couldn’t reach. “I, uh…” he made eye contact with one of the gashes he’d left on Sideswipe’s hip yesterday. “Oh, I’m so sorry! Let me help! What can I do? I’ll do anything! I promise, Sides, I promise!”

Uncomfortable himself, Sideswipe successfully rubbed the back of his neck. “Uh, it’s okay, Grim. You don’t have to do anything. Really, man.”

Grimlock shook his massive head back and forth before thinking better of it and transformed. “No, it’s not okay! I hurt the whole team. I messed up real bad. I gotta fix it.”

Sideswipe sighed dramatically. “Well . . . if you really want to, this gash kinda makes it hard to do some of my chores . . . All of them, actually.”

Grimlock lunged at the opportunity. “I’ll do ‘em all! Don’t you worry ‘bout a thing, Sideswipe, I’ll do them a—”’

“Good to see you found your way back, Sideswipe.”

They turned and Sideswipe shot a cocky grin at Bumblebee. “I’ve got nowhere else to go.”

Bumblebee glanced at Grimlock. “What were you two talking about?”

Grimlock stumbled over himself. “Uh, I was just tellin’ him about the new statue Denny bought.”

Bee hummed. “Funny, I thought I heard that you were going to take over all of Sideswipe’s duties. I must’ve been hearing things.”

“Must’ve,” Sideswipe grumbled.

Their commander let out a heavy sigh. “I thought we talked about this, guys. I said we couldn’t be manipulating each other anymore… Ring a bell?”

Sideswipe shrugged. “Nope. You probably just had a wet dream about it.”

“Sideswipe!”

“Oh, you’re right: Strongarm probably gets off on rules more than you do. My mistake, I must’ve mixed you two up.”

Grimlock was horrified by the snide and disrespect dripping from Sideswipe’s words. He couldn’t understand what was going on between those two.

“Sideswipe, I said no manipulating, and I mean it. Don’t make me—”

“What, ground me? Try, I dare you. We aren’t sparklings, Bee, you gotta get that through your head!” 

The second Bumblebee marched off, Sideswipe turned on Grimlock. His steps towards him were deliberate and heavy: angry. Grimlock backed up a few steps until he bumped into a shelf of Denny’s odd “collectibles.” His tail knocked something over and it shattered on the ground, but Sideswipe didn’t stop moving closer. He walked right up to Grimlock, so close his chassis rubbed against his. Grimlock froze when he felt servos claw at his underbelly. 

“Uh, hey, w-what are you—”

Sideswipe cut Grimlock short when he tapped his interface panels. “I’ve got an idea. Another way you can pay me back; now, open up big boy.” He looped his arms around Grimlock’s neck and twirled his hips, grinding up against the dinobot’s middle. 

Grimlock was still confused, but his body began to react to the onslaught of touch and scent that Sideswipe was offering up. His spike, only half-pressurized, already bumped against its housing, straining to get at the lithe red mech.

“Sideswipe, I—”

“You should transform.” Sideswipe rubbed the heel of his pede against Grimlock’s guarded array. “That would make this a lot more fun.”

Grimlock slipped free from Sideswipe’s grasp and immediately transformed, his processor flooded with hormones and flaring EM fields. “This is how you’ll forgive me?” he asked, optics wide and hopeful.

Sideswipe sauntered forward. “Depends on how well you frag me.” He opened his panels, his red and black, studded spike proudly lifting to attention. Snaking one servo down his body, he slid his digits through the slick mess he’d already made, and lifted his servo back up for Grimlock to smell. “Better work hard.”

Grimlock’s engine revved and he yanked Sideswipe closer, one arm around his waist, and the other holding his wrist so he could lick the taste of Sideswipe off of his own, red digits. “If this is how you will forgive me, I’ll do you better than anyone ever has,” he growled, innocent facade falling away. 

Sideswipe lifted his legs and hooked them around Grimlock’s hips, pressing his open valve flush against Grim’s closed array. “Mmm,” he moaned. “You going to frag me hard?” he whispered right into Grimlock’s ear.

The giant green mech’s engine gave a ferocious rumble and he let go of Sideswipe’s digits to catch his mouth with a hungry kiss. Sideswipe arched, his servos roaming Grimlock’s expansive back, digging into seams and teasing wires. Grimlock broke the kiss, his glossa slipping free.

“Yes,” he rumbled. “I’m going to frag you so hard you’ll scream my name for days.” He bit a jagged line along Sideswipe’s collar. “I’m going to fill you with my fluids until you forget any other name.”

“Primus, Grim, you’re going to make me overload if you keep talking like that,” Sideswipe gasped. He shivered, his valve spreading its moist trail all over Grimlock’s pelvis as he arched and ground against it; searching for any sort of friction. 

Grimlock captured his jaw next, nibbling and sucking so vigorously that the mech in his hold melted. “I’m going to make you do more than overload,” he teased, his voice a low and sultry rumble.

Sideswipe ran his servos over Grimlock’s helm. “Let me go,” he whispered. 

Grimlock did as he said, and the other mech dropped to his knees before him. 

“Open your panels, Grim. I need to feel you. I need to suck on your spike, I need to swallow it right now!” Sideswipe begged. 

The reveal was nothing but impressive. A clash of green and black, the spike was at least triple the size of Sideswipe’s, and transfluid dribbled from the tip, running down the shaft and leaving a wet trail. Sideswipe immediately wrapped both servos around it, valve throbbing when his digits barely touched. 

“Primus, you’re so big!”

Grimlock chuckled his approval. “I’m going to split you apart with this spike. Just wait, you’ll be screaming for more.”

Sideswipe looked up from nuzzling the massive, twitching spike. “Is that a challenge?” Relaxing his jaw, he took the bulbous head of Grimlock’s spike in his mouth, swirling his glossa around the slitted tip and cleaning away the prefluid.

Above him, Grimlock was a moaning mess. He was struggling to keep from thrusting into Sideswipe’s throat. To distract himself, he grabbed the red mech’s hips and, ignoring his cries of surprise, lifted his hips to his face. Sideswipe wrapped his legs around Grimlock’s head and returned to the searing hot spike in his servos. Grim, in the meantime, was nuzzling into the mess of Sideswipe’s valve. He tested the smaller mech’s sweet fluids and groaned, his spike letting out a precursory squirt of transfluid. 

“I —nng— can’t wait to feel you around me,” Grimlock growled possessively as he licked and lapped at Sideswipe’s valve. 

Sideswipe gasped and bobbed his head, sucking Grim’s spike with a renewed fervor. In between tastes, he gasped, “How did you get so great all of a sudden, Grim— ah!”

Grimlock slipped his glossa into Sideswipe’s clenching valve, letting it tour the place like an open house. His nose jutted against the smaller mech’s pulsing anterior node, he flicked his glossa over the roof of the valve and groaned when Sideswipe cried out.

“I’m not new to this,” he rumbled into the other’s valve. “I just don’t show it.” Finished talking, he latched his mouth onto the outside of Sideswipe’s valve and sucked, while his glossa worked furious patterns on the inside. 

Sideswipe trembled in his hold, and he backed off his spike long enough to whine, “G-Grim! Hold on, stop!”

Grimlock immediately detached from his partner. “What’s wrong?”

“I need you to take me. I’m wet enough, just take me!” The dinobot let go of the speedster’s hips and he stood upright, knees wobbly. The giant mech pulled him closer, one servo planted on his aft, and the other slipping down to his valve.

Grimlock slipped one digit into Sideswipe without any resistance. A second was added and he began to thrust, in, out, in, out, the blunt edge of his digits scraping along the closest set of nodes and leaving Sideswipe a cursing, dripping mess. The third was just on the edge of Sideswipe’s limit. He swallowed the sting and took the digit, enveloping it in his warmth, his helm leaning against Grimlock’s massive chest.

“One more digit. Think you can handle it?” Grimlock asked, capturing Sideswipe’s mouth for a brief kiss. 

Huffing and puffing, the red mech responded, “Y-yes.” To reiterate his point, he canted his hips down on the three digits scissoring him, his capillaries frantically clenching and relaxing.

Grimlock’s blunt fourth digit tested the rim of his valve before it inched in with the others in one clean thrust. Sideswipe’s spike plating snapped back immediately, and he bit down on Grimlock’s neck to keep from crying out. Once Grimlock started to thrust his fingers, and stretch Sideswipe even more, the red bot was convinced he could take Grim’s spike. 

“Nng,” he moaned. “P-please, Grimlock, I need you! I need your spike.”

Grimlock licked Sideswipe’s neck and whispered, “After you overload for me.” He thrust faster, digits curling around sensitive nodes. 

The liquid heat settling in the pit of Sideswipe’s stomach obeyed and exploded, sending him crashing into one of the most intense overloads of his life. He cried out in ecstacy, valve clenching needily on the digits stuffing him as his spike gushed transfluid onto both his and Grimlock’s abdomens. 

Grimlock’s spike twitched as he pulled his digits out of Sideswipe and those gorgeous fluids dripped out and coated his spike. He was quick to adjust his hips so that the underbelly of his massive spike pressed flush against Sideswipe’s spasming valve. He groaned and gave a few experimental thrusts, coating himself in the smaller mech’s fluids. Sideswipe was moaning again, and the noise had Grimlock’s fans running overtime, trying to keep his frame cool but not really working. 

Sideswipe moaned and canted his hips against Grimlock’s spike, desperate for touch. Grimlock purred, a sound deep and rumbling that made Sideswipe shiver, and pulled back just enough for his spike to nudge Sideswipe’s slick opening. 

“Primus, Grim, stop teasing!” Sideswipe whined. 

Grimlock grinned and thrust slowly, barely inching into that tantalizingly slick, spasming heat. He groaned as Sideswipe threw his helm back, going slack in his arms. He pushed forward when the resistance let up, and quickly found himself nestled completely inside of the smaller mech. 

“P-Primus,” Grimlock cursed. “You’re so tight.” He ran a servo over Sideswipe’s middle, pleased by the slight ridge his spike made. 

Sideswipe was a blubbering mess when Grimlock started moving, thrusting just enough to create a pleasant amount of friction. He caught his breath long enough to tease, “I’m not screaming yet, pal.”

Grimlock yanked Sideswipe’s leg up so that it was fully extended in the air, like a ballerina. His partner hissed with the stretch, but stopped caring when it exposed a whole new set of nodes in his throbbing valve. Grimlock snapped his hips forward, panting already, and set a cruel pace. He pounded into Sideswipe with abandon, more than happy to sink his spike in and watch the smaller mech’s plating distend. 

Sideswipe bit his lip, holding back ecstatic cries as Grimlock sunk further and further, stuffing him good. “N-nice try,” he gasped.

Grimlock paused mid thrust and captured his lips in a kiss that left no question as to what would come next. When they parted, they were on the ground, Grimlock towering over Sideswipe, spike still half sheathed in his valve. 

Without a word, the mech snapped his hips forward, striking Sideswipe’s ceiling node and forcing a cry out of him, and then Grimlock just stopped. His spike pressed insistently at the node, nearly forcing Sideswipe into another overload, but there wasn’t enough friction. 

“W-what are you doing?” Sideswipe hissed. “Move!”

Grimlock licked his neck. “Beg for it,” he rumbled. 

Sideswipe shivered and bit his lip stubbornly. Grimlock shrugged and propped himself up with his elbows, his optics challenging. They stayed like that for no more than ten seconds, and then Sideswipe cried, “P-please! I beg you, move!”

Grimlock grinned as he were an obliging god, and twirled his hips, grinding the head of his massive spike against Sideswipe’s most sensitive node. Even as Sideswipe overloaded, Grimlock picked up his pace and plowed into him, milking his overload. He cried out, screaming his teammate’s name loud enough for Cybertron to hear.

Grimlock wrapped a fist around Sideswipe’s spike and pumped it in time with his thrusts, moaning louder as he neared his own overload. He thrust again and again, striking every possible node in Sideswipe’s vice-like heat, and his movements became more sporadic. Sideswipe’s charge was already skyrocketing again, and he arched his back to meet Grimlock’s relentless thrusts. 

“Pr-Primus!” Sideswipe cried, canting his hips. “You’re gonne ma—” He screamed, “Grim!” as his third overload racked him.

Grimlock seated himself one last time inside Sideswipe before his spike twitched and spurt transfluid. He stayed seated in Sideswipe as he emptied himself, distending the smaller mechs plating even more, the fluids leaving him more full than he could ever have imagined. Grimlock moaned and gasped, choking on Sideswipe’s name. 

When he finally pulled out, a flood of transfluid followed. “W-was that good enough?” he panted, kissing a trail along Sideswipe’s neck. 

Sideswipe grinned. “Nope. I don’t think that covered my payback.”


End file.
